Sativex(®) (nabiximols, USAN name) oromucosal spray contains the two main active constituents of Cannabis sativa, tetrahydrocannabinol and cannabidiol in a 1:1 molecular ratio, and acts as an endocannabinoid system modulator. Randomized, controlled clinical trials of Sativex as add-on therapy provide conclusive evidence of its efficacy in the treatment of more than 1500 patients with multiple sclerosis (MS)-related resistant spasticity. The primary end point in clinical trials was the mean change from baseline in the 0-10 numerical rating scale (NRS) spasticity score. The first pivotal clinical trial included 189 patients treated for 6 weeks with Sativex (n = 124) or placebo (n = 65). At study end, there was a significant reduction from baseline in patient-recorded NRS spasticity scores with Sativex compared with placebo (-1.18 vs -0.63; p = 0.048). In the second pivotal trial, 337 patients with MS-related resistant spasticity received Sativex (n = 167) or placebo (n = 170) over a 15-week period. In the per-protocol analysis (79% of the patient population), mean baseline NRS spasticity score was reduced significantly in patients receiving Sativex compared with placebo: -1.3 versus -0.8 points (p = 0.035). The third pivotal clinical trial, evaluating the sustained efficacy of Sativex, had a two-phase study design: in phase A (n = 572), 47% of patients were initial responders (improvement ≥ 20%) after 4 weeks of single-blind Sativex treatment who then entered phase B, a randomized, double-blind, 12-week placebo comparison. At the end of phase B, the change in NRS spasticity score improved by a further 0.04 units in initial responders treated with Sativex, but decreased by 0.81 units in placebo recipients (p = 0.0002). Significant improvements in quality-of-life measures from baseline to week 16 were also observed in patients receiving Sativex. The most common treatment-related adverse events with Sativex were mild-to moderate and transient episodes of dizziness, fatigue or somnolence. Sativex does not exhibit the side effects typically associated with recreational cannabis use and there are no signs of drug tolerance or withdrawal syndrome, or any evidence of drug misuse or abuse. Sativex oromucosal spray appears to be a useful and welcomed option for the management of resistant spasticity in MS patients. Although the management of MS has been improved by the availability of disease-modifying agents that target the underlying pathophysiological processes of the disease, a clear need remains for more effective symptomatic treatments, especially as regards MS-related spasticity and pain.